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The microtubule-binding protein CLIP-170 coordinates mDia1 and actin reorganization during CR3-mediated phagocytosis

Elodie Lewkowicz1, Floriane Herit, Christophe Le Clainche

  • 1Institut Cochin, Université Paris Descartes, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 8104, 75014 Paris, France.

The Journal of Cell Biology
|December 31, 2008
PubMed

Insights

Cytoplasmic linker protein 170 (CLIP-170) is crucial for macrophage phagocytosis, controlling actin polymerization via interaction with mDia1. This reveals a novel microtubule-actin cooperation essential for integrin-mediated cellular uptake.

Area of Science:

  • Cell Biology
  • Immunology
  • Cytoskeletal Dynamics

Background:

  • Microtubule dynamics are regulated by plus-end tracking proteins (+TIPs).
  • +TIPs like CLIP-170 and EB1 are key regulators of microtubule behavior.
  • Phagocytosis is a critical cellular process involving cytoskeletal rearrangements.

Purpose of the Study:

  • To investigate the role of +TIPs, specifically CLIP-170 and EB1, in macrophage phagocytosis.
  • To elucidate the molecular mechanisms by which +TIPs influence phagocytosis.
  • To identify novel interactions between microtubule and actin regulatory proteins during phagocytosis.

Main Methods:

  • RNA interference (RNAi) and dominant-negative approaches to deplete or inhibit +TIPs.
  • Assessment of phagocytosis efficiency triggered by alphaMbeta2 integrin/complement receptor activation.
  • Live-cell imaging to track dynamic enrichment of +TIPs at phagocytic cups.
  • Co-immunoprecipitation assays to investigate protein-protein interactions.

Main Results:

  • CLIP-170, but not EB1 or EB3, is specifically required for efficient alphaMbeta2 integrin-mediated phagocytosis.
  • CLIP-170 is dynamically recruited to the phagocytic site, while EB1 is not.
  • CLIP-170 controls the recruitment of the actin-nucleating protein mDia1 during phagocytosis.
  • CLIP-170 directly interacts with mDia1, and this interaction is negatively regulated during phagocytosis.
  • CLIP-170 and mDia1 mediate a novel microtubule-actin cooperation downstream of alphaMbeta2 integrins.

Conclusions:

  • CLIP-170 plays a specific and essential role in regulating actin polymerization during alphaMbeta2 integrin-mediated phagocytosis in macrophages.
  • CLIP-170 acts as a crucial link between microtubule dynamics and actin cytoskeleton remodeling via interaction with mDia1.
  • This study uncovers a novel mechanism of microtubule-actin cooperation critical for immune cell function.

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